This
article was originally published in
The Universal Diver,
and later reprinted as "The case for in-water
recompression". aquaCorps,
No. 11:35-46.

In-water Recompression as
an Emergency Field Treatment of Decompression Illness

Richard L. Pyle

and

David A. Youngblood

Abstract

In-Water Recompression
(IWR) is defined as the practice of treating divers suffering
from Decompression Sickness (DCS) by recompression underwater
after the onset of DCS symptoms. The practice of IWR
has been strongly discouraged by many authors, recompression
chamber operators, and diving physicians. Much of the opposition
to IWR is founded in the theoretical risks associated with
placing a person suffering from DCS into the uncontrolled underwater
environment. Evidence from available reports of attempted IWR
indicates an overwhelming majority of cases in which the
condition of DCS victims improved after attempted
IWR. At least three formal methods of IWR have been published.
All of them prescribe breathing 100% oxygen for prolonged periods
of time at a depth of 30 feet (9meters), supplied via a full face
mask. Many factors must be considered when determining whether
IWR should be implemented in response to the onset of DCS. The efficacy of IWR and the
ideal methodology employed cannot be fully determined without
more careful analysis of case histories.

Introduction

There are many
controversial topics within the emerging field of
"technical" diving. This is not surprising, considering
that technical diving activities are often high-risk in nature
and extend beyond widely accepted "recreational" diving
guidelines. Furthermore, many aspects of technical diving involve
systems and procedures which have not yet been entirely validated
by controlled experimentation or by extensive quantitative data.
Seldom disputed, however, is the fact that many technical divers
are conducting dives to depths well in excess of 130 feet for
bottom times which result in extensive decompression obligations, and that these more
extreme dive profiles result in an increased potential for
suffering from Decompression Sickness (DCS).

Although technical
diving involves sophisticated equipment and procedures designed
to reduce the risk of sustaining DCS from these more extreme
exposures, the risk nevertheless remains significant. Along with
this increased potential for DCS comes an increased need for many
"technical" divers to be aware of, and be prepared for,
the appropriate implementation of emergency procedures in
response to DCS. In the words of Michael Menduno
(1993),
"The solution for the technical community is to expect and
plan for DCS and be prepared to deal with
it".

There is almost
universal agreement on the practice of administering oxygen to
divers exhibiting symptoms of DCS. This practice is strongly
supported both by theoretical models of dissolved-gas physiology,
and by empirical evidence from actual DCS cases. The answer to the
question of how best to treat the afflicted diver beyond the
administration of oxygen, however, is not as widely agreed upon.
Perhaps the most controversial topic in this area is that of
In-Water Recompression (IWR); the practice of treating a diver
suffering from DCS by placing them back underwater
after the onset of DCS symptoms, using the pressure
exerted by water at depth as a means of recompression.

At one extreme of this
controversy is conventional conviction: divers showing signs of DCS should never, under any
circumstances, be placed back in the water. As pointed out by
Gilliam and Von Maire (1992, p.
231), "Ask
any hyperbaric expert or chamber supervisor their feelings on
in-the-water recompression and you will get an almost universal
recommendation against such a practice." Most diving
instruction manuals condemn IWR, and the Divers Alert Network
(DAN) Underwater Diving Accident & Oxygen First Aid Manual
states in italicized print that "In-water recompression
should never be attempted" (Divers Alert Network, 1992, p.
7).

On the other hand, IWR
for treatment of DCS is a reality in many fields of
diving professionals. Abalone divers in Australia (Edmonds,
et al., 1991; Edmonds, 1993) and diving fishermen in Hawaii
(Farm et al., 1986; Hayashi, 1989; Pyle, 1993) have relied on IWR for the
treatment of DCS on repeated occasions. Many of
these individuals walking around today might be dead or confined
to a wheelchair had they not re-entered the water immediately
after noticing symptoms of DCS.

At the root of the
controversy surrounding this topic is a clash between theory and
practice.

IWR
in Theory

There are many important
reasons why the practice of IWR has been so adamantly
discouraged. The idea of placing a person who is suffering from a
potentially debilitating disorder into the harsh and
uncontrollable underwater environment appears to border on
lunacy. Hazards on many levels are increased with immersion, and
the possibility of worsening the afflicted diver's condition is
substantial.

The most often cited
risk of attempted IWR is the danger of adding more nitrogen to
already saturated tissues. Using air or Enriched Air Nitrox (EAN) as a breathing gas during
attempted IWR may lead to an increased loading of dissolved
nitrogen, causing a bad situation to become worse. Furthermore,
the elevated inspired partial pressure of nitrogen while
breathing such mixtures at depth leads to a reduced nitrogen
gradient across alveolar membranes, slowing the rate at which
dissolved nitrogen is eliminated from the blood (relative to
breathing the same gas at the surface).

The underwater
environment is not very conducive to the treatment of a diver
suffering from DCS. Perhaps the most obvious
concern is the risk of drowning. Depending on the severity of the
DCS symptoms, the afflicted diver
may not be able to keep a regulator securely in his or her mouth.
Even if the diver is functioning nearly perfectly, the risk of
drowning while underwater far exceeds the risk of drowning while
resting in a boat. Another complicating factor is that
communications are extremely limited underwater. Therefore,
monitoring and evaluating the condition of the afflicted diver
(while they are performing IWR) can be very difficult.

In almost all cases,
attempts at IWR will occur in water which is colder than body
temperature. Successful IWR may require several hours of
down-time, and even in tropical waters with full thermal diving
suits, hypothermia is a major cause for concern. Exposure to cold
also results in the constriction of peripheral circulatory
vessels and decreased perfusion, reducing the efficiency of
nitrogen elimination (Balldin, 1973; Vann, 1982). In addition to cold, other
underwater environmental factors can decrease the efficacy of
IWR. Strong currents often result in excessive exertion, which
may exacerbate the DCS problems. (Although exercise can
increase the efficiency of decompression by increasing circulation rates
and/or warming the diver [Vann, 1982], it may also enhance the
formation and growth of bubbles in a near- or post-DCS situation.) Depending on the
geographic location, the possibility of complications resulting
from certain kinds of marine life (such as jellyfish or sharks),
cannot be ignored.

Published methods of IWR
prescribe breathing 100% oxygen at a depth of 30 feet (9 meters)
for extended periods of time. Such high oxygen partial pressures
can lead to convulsions from acute oxygen
toxicity, which
can easily result in drowning.

Another often overlooked
disadvantage of immersion of a diver with neurological DCS symptoms is that detection of
those symptoms by the diver may be hampered: the
"weightless" nature of being underwater can make it
difficult to assess the extent of impaired motor function, and
direct contact of water on skin may affect the diver's ability to
detect areas of numbness. Thus, an immersed diver may not be able
to determine with certainty whether or not symptoms have
disappeared, are improving, are remaining constant, or are
getting worse.

The factors described
above are all very serious, very real concerns about the practice
of IWR. There are really only two main theoretical advantages to
IWR. First and foremost, it allows for immediate
recompression (reduction in size) of intravascular or other
endogenous bubbles, when transport to recompression chamber
facilities is delayed or when such facilities are simply
unavailable. Bubbles formed as a result of DCS continue to grow for hours after
their initial formation, and the risk of permanent damage to
tissues increases both with bubble size and the duration of
bubble-induced tissue hypoxia. Furthermore, Kunkle and Beckman (1983) illustrate that the time
required for bubble resolution at a given overpressure increases
logarithmically with the size of the bubble. Farm,
et al. (1986, p. 8) suggest that "Immediate
recompression within less than 5 minutes (i.e. when
the bubbles are less than 100 micrometers in diameter)
is...essential if rapid bubble dissolution is to be
achieved" (italics added). If bubble size can be immediately
reduced through recompression, blood circulation may be restored
and permanent tissue damage may be avoided, and the time required
for bubble dissolution is substantially shortened. Kunkle and Beckman, in discussing the treatment of
central nervous system (CNS) DCS, write:

"Because
irreversible injury to nerve tissue can occur within 10 min
of the initial hypoxic insult, the necessity for immediate
and aggressive treatment is obvious. Unfortunately, the time
required to transport a victim to a recompression facility
may be from 1 to 10 hours [Kizer, 1980]. The possibility of
administering immediate recompression therapy at the accident
site by returning the victim to the water must therefore be
seriously considered." (p. 190)

The second advantage
applies only when 100% oxygen is breathed during IWR. The
increased ambient pressure allows the victim to inspire elevated
partial pressures of oxygen (above those which can be achieved at
the surface). This has the therapeutic effect of saturating the
blood and tissues with dissolved oxygen, enhancing oxygenation of
hypoxic tissues around areas of restricted blood flow.

There is also some
evidence that immersion in and of itself might enhance the rate
at which nitrogen is eliminated (Balldin and Lundgren, 1972); however, these effects are
likely more than offset by the reduced elimination resulting from
cold during most IWR attempts.

IWR
in Practice

Three different methods
of IWR have been published. Edmonds et al., in their first edition of Diving
and Subaquatic Medicine (1976), outlined a method of IWR
using surface-supplied oxygen delivered via a full face mask to
the diver at a depth of 9 meters (30 feet). According to this
method, the prescribed time an treated diver spends at 9 meters
varies from 30-90 min depending on the severity of the symptoms,
and the ascent rate is set at a steady 1 meter per 12 min (~1
ft/4 min). This method of IWR was expanded and elaborated upon in
the 2nd Edition (1981), and again in the 3rd
Edition (1991);
and has come to be known as the "Australian Method". It
has also been outlined in other publications (Knight,
1984; 1987; Gilliam and von Maier, 1992; Gilliam, 1993; Edmonds, 1993), and is presented in Appendix A
of this article. [NOTE: Appendices are not included on
this web page].

The U.S. Navy Diving
Manual (Volume 1, revision 1, 1985) briefly outlines a method of IWR
to be used in an emergency situation when 100% oxygen rebreathers
are available. Gilliam (1993, p. 208) proposed that this method could
"easily be adapted to full facemask diving systems or
surface supplied oxygen". It involves breathing 100% oxygen
at a depth of 30 feet (9 meters) for 60 min in so-called
"Type I" (pain only) cases or 90 min in "Type
II" (neurological symptoms) cases, followed by an additional
60 min of oxygen each at 20 feet (6 meters) and 10 feet (3
meters). This method is outlined in Gilliam
(1993), and in
Appendix B of this article. [NOTE: Appendices are not
included on this web page].

The third method,
described in Farm et al. (1986), is a modification of the
Australian Method which incorporates a 10-minute descent while
breathing air to a depth 30 feet (9 meters) greater than the
depth at which symptoms disappear, not to exceed a maximum depth
of 165 feet (50 meters). Following this brief
"air-spike", the diver then ascends at a decreasing
rate of ascent back to 30 feet (9 meters), where 100% oxygen is
breathed for a minimum of 1 hour and thereafter until either
symptoms disappear, emergency transport arrives, or the oxygen
supply is exhausted. This method of IWR, developed in response to
the experiences of diving fishermen in Hawaii, has come to be
known as the "Hawaiian Method". This method is
described in Appendix C of this article. [NOTE:
Appendices are not included on this web page].

All three of these
methods share the requirement of large quantities of oxygen
delivered to the diver via a full face mask at 30 feet (9 meters)
for extended periods, a tender diver present to monitor the
condition of the treated diver, and a heavily weighted drop-line
to serve as a reference for depth. Also, some form of
communication (either electronic or pencil and slate) must be
maintained between the treated diver, the tending diver, and the
surface support crew.

Information on at least
535 cases of attempted IWR has been reported in publications.
Summary data from the majority of these attempts are included in Farm
et al. (1986), who present the results of
their survey of diving fishermen in Hawaii. Of the 527 cases of
attempted IWR reported during the survey, 462 (87.7%) involved
complete resolution of symptoms. In 51 cases (9.7%), the diver
had improved to the point where residual symptoms were mild
enough that no further treatment was sought, and symptoms
disappeared entirely within a day or two. In only 14 cases (2.7%)
did symptoms persist enough after IWR that the diver sought
treatment at a recompression facility. None of the divers
reported that their symptoms had worsened after IWR. It is also
interesting (and somewhat disturbing) to note that none of the
divers included in this survey were aware of published methods of
IWR (i.e. all were "winging it" - inventing the
procedure for themselves as they went along), and all had used
only air as a breathing gas.

Edmonds et al. (1981) document two cases of successful
IWR in which divers suffering from DCS in remote locations followed the
Australian Method of IWR with apparently tremendous success (both
are presented below as Case #8 and #9). Overlock
(1989) described
six cases of DCS involving divers using decompression computers. Of these, four
involved attempted IWR, three of which were apparently successful
(the results from the fourth case are unclear). Two of these
cases are described as Case #1 and Case #4 below. Hayashi
(1989) reported
two cases of attempted IWR, one of which involved the use of 100%
oxygen, and the other, involving air as a breathing gas, was also
described in Farm et al. (1986) and is described below as Case #2.

At present, we are aware
of about twenty additional cases of attempted IWR which have not
previously been reported in literature. Of these, two resulted in
the death of the attempting divers (both divers were together at
the time - see Case #3 below), and one resulted in an
apparent aggravation of the conditions (i.e. turning a
sore shoulder into permanent quadriplegia - see Case #10 below). Another case, for which
we do not have details, involved a diver who apparently worsened
his condition with IWR, but eventually recovered after proper
treatment in a recompression chamber facility. In six other
cases, the condition of the diver had remained constant or
improved after attempted IWR, and further treatment in a
recompression chamber was sought by most of them. In all of the
remaining cases, the diver was asymptomatic after IWR, they
sought no further treatment, and their symptoms did not return.

Without doubt, many more
attempts at IWR have occurred but have not been reported. Edmonds, et al. (1981, p.
175), in
discussing the practice of the Australian Method of IWR, note
that "Because of the nature of this treatment being applied
in remote localities, many cases are not well documented. Twenty
five cases were well supervised before this technique increased
suddenly in popularity, perhaps due to the success it had
achieved, and perhaps due the marketing of the [proper]
equipment..." Several professional divers have privately
confided to one of us (RLP) that they have used IWR to treat
themselves and companions on multiple occasions, and all have
reported great success in their efforts. Some continue to teach
the practice to their more advanced students (although the
practice was once taught on a more regular basis, it has since
fallen out of widely accepted instruction protocol).

Evaluation
of Case Histories

In determining the
relative value of IWR as a response to DCS, it is perhaps most useful to
carefully examine case histories involving attempted IWR. DCS is, by nature, a very complex,
dynamic, and unpredictable disorder, and evaluation of the role
of IWR as a treatment in reported cases is often difficult.
Assessing the success or failure of an attempt at IWR is obscured
by the fact that a positive or negative change in the victim's
condition may have little or nothing to do with the IWR treatment
itself. Furthermore, even the determination of whether or not a DCS victim's condition was better or
worse after attempted IWR is not always clear. For example,
consider the following case, first reported by Overlock
(1989):

Five minutes after
surfacing from the fourth dive to moderate depth (75-120
feet) over a 24 hr period, a diver developed progressive arm
and back weakness and pain. She returned to 60 feet for 3
min, then ascended (decompressed) over a 50-minute period
(with stops at 30, 20, and 10 feet), breathing air. Tingling
and pain resolved during the first 10 min of IWR. Three hours
after completing IWR, she developed numbness in the right leg
and foot, and reported "shocks" running down both
legs, whereupon she was taken to a recompression chamber.
After 3 successive U.S. Navy "Table 6" treatments,
she still felt weakness and some decreased sensation.

The effect of IWR on the
recovery of this diver is unclear. Although the pain and weakness
were resolved during IWR, more serious symptoms developed hours
afterward. Perhaps numbness would never have developed had the
diver been taken directly to a recompression chamber instead of
re-entering the water, in which case she may have responded to
treatment without residuals. On the other hand, had she not
returned to the water, the initial symptoms may have progressed
into paralysis during her evacuation to the chamber, and she
might have ultimately suffered far more serious and debilitating
residuals. Cases such as this do not contribute much insight into
the efficacy of IWR.

Other cases, however,
provide stronger evidence suggesting that IWR has been of
benefit. Consider the following case documented in Farm
et al. (1986) and Hayashi
(1989):

"Four fisherman
divers were working in pairs at a site about 165 to 180 feet
deep. Each pair alternated diving and made two dives at the
site. Both divers of the second pair rapidly developed signs
and symptoms of severe CNS decompression sickness upon surfacing from their
second dive. The boat pilot and the other diver decided to
take both victims to the U.S. Navy recompression chamber and
headed for the dock some 30 minutes away [the recompression
chamber was an additional hour away from the dock]. During
transport, one victim refused to go and elected to undergo
in-water recompression, breathing air. He took two full scuba
tanks, told the boat driver to come back and pick him up
after transporting the other bends victim to the chamber, and
rolled over the side of the boat down to a depth of 30 to 40
feet. The boat crew returned after 2 hours to pick him up. He
was asymptomatic and apparently cured of the disease. The
other diver died of severe decompression sickness in the Med-Evac helicopter
en route to the recompression chamber." (Hayashi,
1989, p. 157)

This is just one example
of many which provide compelling evidence that IWR can, in some
circumstances, result in dramatic relief of serious DCS symptoms.
Ironically, had this incident occurred in an area where a
recompression chamber was not an option, both divers would
probably have opted for IWR, and the less fortunate victim might
possibly have survived the ordeal.

On the other hand,
attempts at IWR under inappropriate circumstances can lead to
tragedy, as is clearly evident from the following case:

Twelve experienced
divers conducted an 18-minute dive on a wreck in about 215
feet. They surfaced following 38 minutes of air decompression, at which time two of the
divers reported "incomplete decompression". These two divers
obtained additional supplies of air and returned to the water
in an apparent effort to treat DCS symptoms. They never
returned to the boat, and their bodies were recovered two
weeks later.

The reason for their
deaths remains a mystery. It is possible that they were suffering
from neurological DCS symptoms, and drowned as a
result of these symptoms. The tragedy of this case lies in the
fact that they most likely would have survived had they not
re-entered the water. The boat was equipped with 100% oxygen
(surface-breathing) equipment, and the incident occurred in an
area where emergency air-transport could have delivered the
divers to a recompression chamber less than an hour after
surfacing. The water temperature in this case was about 61-63 F
(16-17 C), and the surface conditions
were relatively rough (3-5 ft seas). Whether or not these divers
perished as a direct result of DCS symptoms, they would, in all
likelihood, have survived the incident had they not returned to
the water.

The main potential
benefit of IWR lies in the ability to recompress the DCS victim immediately after
the onset of DCS symptoms, before intravascular
bubbles have a chance to grow or cause serious permanent damage.
The apparent success of many reported attempts of IWR may be
attributed to the immediacy of the recompression. In one case,
reported by Overlock (1989), IWR began before the diver even
reached the surface:

After ascending from
his second 10-minute dive to 190 feet, a diver followed the decompression `ceilings' suggested by his
dive computer. As he was nearing the end of his computer's
suggested decompression schedule, he suddenly
noticed weakness and incoordination in both arms, and
numbness in his right leg. He immediately descended to a
depth of 80 feet where, after 3 min, the symptoms
disappeared. After a total of 8 min at 80 feet, he slowly
ascended over a period of 50 min to 15 feet (his companion
supplied him with fresh air tanks). He remained at this depth
until his decompression computer had
"cleared". He felt tired after surfacing, but was
otherwise asymptomatic.

In many other cases, IWR
was commenced within a few minutes after surfacing, usually
resulting in the elimination or substantial reduction of
symptoms. In cases where DCS results from gross omission of
required decompression, divers may anticipate the
probable consequences, and often return immediately to depth as
soon as possible in an effort to complete the required decompression. Two such cases are presented
here:

While conducting a
solo dive at a depth of 195 feet, a diver became entangled in
lines and mesh bags. In his struggles to free himself, he
extended his time at depth well beyond the intended 10
minutes, and squandered much of the air he had expected to
use for decompression. Upon freeing himself, he
immediately began his ascent, but was mortified to discover
that the boat anchor had broken loose and was gone. Swimming
down-current, he fortuitously saw the anchor dragging across
the bottom, and quickly caught up with the anchor line at a
depth of 60 feet. At this time, his decompression computer indicated a
`ceiling' of 70 feet, and his pressure gauge showed that his
scuba tank was nearly empty. He slowly ascended to the
surface and quickly explained his predicament to his
companion in the boat. While waiting for his companion to rig
a regulator to a fresh tank of air, he began feeling symptoms
of severe dizziness and had problems with his vision.
Grasping the second tank under his arm, he allowed himself to
sink back down, nearly losing consciousness. Upon reaching a
depth of 80 feet, his clouded consciousness fully resolved,
and he remained 10-15 ft below his computer's recommended
`ceiling' during subsequent decompression. Although he eventually
exited the water before his computer had "cleared",
he did not experience any additional symptoms.

A diver had
partially completed his decompression following 15 minutes at 200
feet, when he suddenly became aware of the presence of a very
large and somewhat "inquisitive" Tiger Shark.
Initially, the diver maintained his composure, fearing DCS more than the threat of
attack. When the shark rose above, passing between the diver
and the boat, the diver reconsidered the situation and opted
to abort decompression. After a rapid ascent from
about 40 feet, the diver hauled himself over the bow of the
17-foot Boston Whaler (without removing his gear).
Anticipating the onset of DCS, he instructed his startled
companion to quickly haul up the anchor and drive the boat
rapidly towards shallower water. By the time they
re-anchored, the diver was experiencing increasing pain in
his left shoulder. He re-entered the water and completed his decompression, emerging asymptomatic.

There are many other
cases in which divers must interrupt their decompression temporarily, then resume decompression within a few minutes without
ever experiencing symptoms of DCS. Generally, these cases of
asymptomatic `interrupted decompression' are not considered as IWR.
However, one such incident which recently occurred in Australia
is worth mentioning:

After spending 18
minutes at a depth of 220 feet, a diver experienced a serious
malfunction of her Buoyancy Compensator inflation device
which resulted in the rapid loss of her air supply and a
sudden increase in her buoyancy. Additionally, she became
momentarily entangled in a guide line, further delaying
ascent, and was freed from the line with the assistance of
her diving companion. As they ascended, they were met by a
second team of divers just beginning their descent. Although
one of the members of the second team was able to provide her
with air to breathe, he was unable to deflate her
over-expanded B.C., and both ascended rapidly to the surface.
Within 4 minutes, she returned to a depth of 20 feet where
she breathed 100% oxygen for 30 min. She then ascended to 10
feet where she completed an additional 30 min of breathing
oxygen. Upon surfacing, she was taken to a nearby
recompression chamber facility, breathing oxygen during the
30 min required for transport. Arriving at the facility, she
noticed no obvious symptoms of DCS, but was diagnosed with mild
"Type II" DCS and treated several times in
the chamber. She suffered no apparent residual effects.

Although no DCS symptoms developed prior to
recompression, serious symptoms undoubtedly would have ensued had
recompression not been immediate, given the extent of the
exposure and the explosive rate of ascent. It is interesting that
a modified version of the Australian Method of IWR was employed,
rather than the diver descending to greater depth on air to
complete the omitted decompression. Recompression depth was limited
to a maximum of 20 feet due to concerns of oxygen
toxicity at
greater depths. The victim was monitored continuously while
breathing oxygen underwater by at least two tending divers.

It should be noted that
successful attempts at IWR are not limited to cases which take
advantage of the ability to immediately recompress the victim. Edmonds et al. (1981) report on a case where IWR
yielded favorable results many hours after the initial onset of DCS:

After a second dive
to 100 feet, a diver omitted decompression due to the presence of an
intimidating Tiger Shark. Within minutes of surfacing, he
"developed paraesthesia, back pain, progressively
increasing incoordination, and paresis of the lower
limbs". After two unsuccessful attempts at air IWR,
arrangements were made to transport the victim to a hospital
100 miles away. He arrived at the hospital 36 hours after the
onset of symptoms, and due to adverse weather conditions, he
could not be transported to the nearest recompression chamber
(2,000 miles away), for an additional 12 hours. By this time,
the victim was "unable to walk, having evidence of both
cerebral and spinal involvement", manifested by many
severe neurological ailments. The diver was returned to the
water to a depth of 8 meters, where he breathed 100% oxygen
for 2 hours, then decompressed according to the Australian
Method of IWR. Except for small areas of hypoaesthesia on
both legs, all other symptoms had remised at the end of the
IWR treatment.

This case suggests that
in-water oxygen treatment in depths as little as 8 meters can
have positive effects on DCS symptoms even after much time
has elapsed. It also underscores another aspect of IWR; the fact
that it may be the only treatment available in remote
areas where recompression chamber facilities are many thousands
of miles and several days away. For example, Edmonds et al. (1981) report on another case which
occurred in the Solomon Islands. At the time, the nearest
recompression chamber was 3,500 km away and prompt air transport
was unavailable:

Fifteen minutes
after a 20-min dive to 120 feet, and 8 min of decompression, a diver developed severe
neurological DCS symptoms, including
"respiratory distress, then numbness and paraesthesia,
very severe headaches, involuntary extensor spasms, clouding
of consciousness, muscular pains and weakness, pains in both
knees and abdominal cramps". No significant improvement
occurred after 3 hours of surface-breathing oxygen. She was
returned to the water where she followed the "Australian
Method" of IWR (breathing 100% oxygen at 9 meters [30
feet]). Her condition was much improved after the first 15
minutes, and after an hour she was asymptomatic, with no
recurring symptoms.

Although most of the
reported attempts at IWR have utilized only air as a breathing
gas, this practice has been strongly discouraged due to the risks
of additional nitrogen loading. The concern that air-only IWR may
transform an already bad situation into tragedy seems clearly
validated by the following case:

A young diver
experienced pain-only symptoms of DCS after an unknown dive
profile. He made three successive attempts at IWR (presumably
breathing air), each time worsening his condition. After the
third attempt, his condition had degenerated into
quadriplegia. Because of transport delays, he did not arrive
at a recompression chamber until about three days after the
incident. Saturation treatment yielded no improvement in his
condition, and he remained permanently paralyzed.

Whereas the above case
illustrates an unsuccessful attempt to treat relatively mild
symptoms of DCS with air-only IWR, the following
case, reported by Farm et al. (1986), represents an apparently
successful attempt at treating very severe symptoms with similar
techniques:

Shortly after a
third dive to 120-160 feet, a diver developed
"uncontrollable movements of the muscles of his
legs". Within a few minutes, his condition deteriorated
to the point where he was paralyzed; numb from the
nipple-line down and unable to move his lower extremities. He
was able to hold a regulator in his mouth, so a full scuba
tank was strapped to his back and he was rolled into the
water to a waiting tender diver. The tender verified that the
victim was able to breathe, and proceeded to drag him down to
35-40 feet. When the symptoms did not regress, the victim was
pulled deeper by the tender. At 50 feet, he regained control
of his legs and indicated that he was feeling much better. He
was later supplied with an additional scuba tank, ascended to
25 feet for a period of time, and then finished his second
tank at 15 feet. Except for feeling "a little
tired" that evening, he regained full strength in his
arms and legs and remained asymptomatic.

Another, previously
unpublished case, involved a DCS victim whose symptoms were so
severe that IWR was not attempted for fear that he would drown:

Four aquarium fish
collectors ascended rapidly from their second 200 feet dive
of the day, aborting essentially all decompression. All immediately began
experiencing nausea and varying degrees of neurological DCS symptoms. Three of the
divers returned to a depth of about 50 feet, but the fourth
opted instead to stay in the boat. When the three completed
their abridged attempt at IWR (after which all three felt
noticeably improved), they headed for shore. Help was
summoned, and additional scuba tanks and 100% oxygen were
obtained and loaded into the boat. By this time, one of the
divers felt only pain in his shoulders, and the other three
were experiencing varying degrees of neurological DCS symptoms. The worst of these
was diver who did not attempt IWR immediately after the
initial onset of symptoms: he was unable to move his arms or
legs and was having difficulty breathing. The other three
attempted to assist him back in the water, but they
eventually gave up, fearing that he might drown (due to his
inability to hold the regulator in his mouth). The other
three continued IWR, breathing both air and 100% oxygen at
30-40 feet, until nightfall forced them out of the water.
That night, all four took turns breathed 100% oxygen on the
surface while waiting for the emergency evacuation plane to
arrive. The following day, the three who had attempted IWR
were flown to Honolulu, where they experienced varying
degrees of recovery after treatment in a recompression
chamber. The one who did not attempt IWR died before the
plane arrived.

All of the cases
described thus far have involved either 100% oxygen or air (or
both) as breathing gasses during IWR. In at least one reported
case, EAN was used as a breathing gas for
the IWR treatment:

After spending 25
minutes at a maximum depth of 147 feet, a diver ascended
following decompression stops required by his
tables. He began feeling a tingling sensation and sharp pain
in his right elbow as he arrived at his 30 feet decompression stop. He completed an
additional 30 min at 10 feet beyond what was called-for by
his tables, and then surfaced. His symptoms subsided somewhat
after an hour of breathing 100% oxygen on the boat, but
persisted enough to prompt the diver to attempt IWR. He
returned to the water with an additional cylinder containing EAN-50 (50% oxygen, 50%
nitrogen) and descended to 100 feet for a period of 10
minutes. He ascended to 20 feet over a 10-minute period, and
remained there for 68 min. He spent an additional 5 min at 10
feet, then surfaced asymptomatic, with no recurrence of
symptoms.

This case illustrates
another fundamental risk associated with IWR; that of acute CNS oxygen
toxicity. During
the deepest portion of above IWR profile, the diver was breathing
an oxygen partial pressure of 2.02, considerably greater than
what is considered safe. The diver was aware of the potential for
acute CNS oxygen toxicity and had an additional cylinder
of air with him, just in case. Furthermore, he was exposed to
this excessive oxygen partial pressure for only 10 minutes.

Discussion

As stated earlier, the
source of controversy surrounding the topic of in-water
recompression is essentially the conflict between what is
predicted by theory, and what appears to be demonstrated by
practice. In reviewing the issue of IWR, several questions
require attention. First and foremost, should IWR ever be
attempted under any circumstances? If the answer is
"yes", then under what circumstances should it be
performed? Also, if the decision to perform IWR has been made,
which method should be followed?

The
Efficacy of IWR

From the cases described
above, it should be evident that IWR has almost certainly been of
benefit to some DCS victims in certain
circumstances. If the selection of cases seems biased towards
"successful" attempts at IWR, it is only a reflection
of the numbers of actual cases on record. Whereas only one
additional attempt at IWR (besides Case #3 and #10) clearly led to deterioration of
the condition of a DCS victim, there are literally hundreds
of additional cases where IWR was almost certainly of (sometimes
great) benefit.

Opponents to the
practice of IWR are usually quick to point out that DCS symptoms are often relieved,
sometimes substantially, when the victim breathes 100% oxygen at
the surface (the presently accepted and recommended response to DCS). Indeed, if symptoms do resolve
with surface-oxygen, and recompression treatment facilities are
relatively close at hand (via emergency transport), then the
additional risks incurred with re-immersion seem unwarranted. The
two deceased divers discussed in Case #3 would have, in all likelihood,
survived their ordeal if oxygen was administered on the boat and
transport to the nearby recompression chamber was effected.
However, in cases where chamber facilities are not available, or
when symptoms persist in spite of surface-oxygen (such as in Case #9 and #13), then recompression is clearly
necessary, and IWR perhaps should be attempted.

Determining
Circumstances Appropriate for IWR

It should also be clear
that identifying those circumstances under which IWR should be
implemented is an exceedingly difficult task. A wide variety of
variables must be taken into account, and many factors must be
carefully considered. Although the decision to perform IWR should
be made quickly, it should not be made in haste.

Hunt
(1993) pointed
out that DCS often carries with it a certain
stigma. Under some circumstances, a diver suffering from the
onset of DCS symptoms may be reluctant to
reveal their condition to companions. Consequently, such an
individual might attempt IWR so as to "fix" themselves
without anyone else becoming aware of the problem. For obvious
reasons, this alone is not a reasonable justification for
considering IWR, and is especially dangerous because it likely
results in the diver attempting IWR without the safety of an
observing attendant or tender. Similarly, IWR should never
be thought of as a substitute for proper treatment in a
recompression chamber. IWR is not a "poor man's"
treatment, and the decision to implement it should not be
motivated by financial concerns. Regardless of the outcome of an
IWR attempt, medical evaluation by a trained hyperbaric
specialist should always be sought as soon afterward as
possible.

The major factor in
determining whether IWR should be implemented is the distance and
time to the nearest recompression facility. In a study of more
than 900 cases of DCS in U.S. Navy divers, Rivera
(1963) found
that 91.4% of the cases treated within fifteen minutes were
successful, whereas the success rate when treatment was delayed
12-24 hours was 85.7%. A similar study on DCS cases among sport (recreational)
divers showed similar results. Of 394 examined cases, 56% of
divers with mild DCS symptoms achieved complete
relief when treated within 6 hours, whereas only 30% were
completely relieved when treatment was delayed 24 hours or more.
The same study found that 39% of divers with severe symptoms were
relieved when treated within 6 hours, whereas only 26% were
relieved when treatment was delayed 24 hours or more (Divers Alert Network, 1988). In reviewing these numbers,
Moon (1989) stressed that delay of treatment for DCS should be minimized, but also
noted that response to delayed treatment is not entirely
unacceptable. Knight (1987) recommends that IWR should be
considered when the nearest recompression facility is more than 6
hours away. Such generalizations are difficult to make, however,
as indicated by the fact that the ill-fated diver in Case #2 was less than 2 hours away from
a recompression chamber.

One of the most
important variables affecting the decision to attempt IWR is the
mental and physical state of the diver. Certainly divers who are,
for whatever reason, uncomfortable or reluctant to return to the
water for IWR should not be coerced or forced to do so. The
extent and severity of the DCS symptoms are also important
factors. Whether or not mild DCS symptoms (i.e. pain-only)
should be treated is not certain. One perspective is that such
symptoms are not likely to leave the diver permanently disabled,
and thus the risks associated with attempted IWR would not be
worth taking. Furthermore, individuals with such symptoms are
prime candidates for "making a bad situation worse" (as
was demonstrated in Case #10). Conversely, the risks of
submerging severely incapacitated divers might override the
potential benefits of IWR when serious neurological
manifestations are evident. Edmonds (1993) recommends against the practice
of IWR in situations "where the patient has either epileptic
convulsions or clouding of consciousness."The death of the
two divers in Case #3 might have resulted from
drowning due to loss of consciousness from severe neurological
symptoms. However, some evidence indicates that IWR may be of
value even under these circumstances. Although the divers treated
in some cases (e.g. #2, #5, and #11) might have gone unconscious
underwater and drowned, the consequences of no immediate
recompression may have been equally grave. Also, the diver who
perished in Case #12 may have survived had he
performed IWR along with his companions.

The immediacy of
recompression may be particularly advantageous if DCS symptoms develop soon after
surfacing from a deep dive, and when these symptoms are
neurological and "progressive" (sensuFrancis, et al., 1993). Under such circumstances, the
condition of the DCS victim can rapidly degenerate,
and permanent damage may ensue in the absence of immediate
recompression. However, it is also particularly critical in these
circumstances to monitor the condition of the treated diver with
a tender close by.

As mentioned earlier,
environmental factors such as water temperature, surface
conditions, hazardous marine life, and strong currents might
significantly influence the feasibility of IWR. Many technical
dives are conducted in relatively cold water (such as Europe, the
northeastern and western coasts of the continental United States,
southern Australia, and many freshwater systems), and the risk of
hypothermia and decreased nitrogen elimination rates create
additional complications for attempted IWR in these environments.
Edmonds et al. (1981) and Edmonds
(1993) have
pointed out that reduced water temperature is not necessarily as
great a concern as many opponents of IWR have suggested. The
reasoning is that divers in these environments are usually
well-equipped with thermal protection such as dry-suits, which
have come into wide-spread use among technical divers. If the
divers have adequate thermal protection to conduct the initial
dive, then they are likely prepared to tolerate additional
in-water exposure during IWR. However, Sullivan and Vrana (1992) reported on two cases of
simulated IWR off Antarctica in - 1.4C water, and concluded that
"[IWR] cannot be considered sufficiently reliable in
[extremely] cold waters..." protection.

Sharks and other
hazardous marine life can tremendously complicate IWR efforts. In
Case
#5, a large
Tiger Shark did appear during IWR, but did not influence the
diver's ascent profile. Divers omitted required decompression in Case #6 and #8 due to the presence of large
Tiger Sharks, thus leading to subsequent attempts at IWR. The
risks of this threat are generally minuscule, however these cases
illustrate that such problems can occur.

In addition to the
factors discussed above, the availability of large quantities of
100% oxygen and the equipment needed to deliver it safely to a
diver 30 feet (9 meters) underwater are also very important
factors when considering an attempt at IWR. These factors are
discussed in greater detail in the following section.

Methodology
of IWR

Once the decision to
perform IWR has been made, the next question to consider concerns
methodology. The fundamental difference between the Australian
Method and the Hawaiian Method of IWR is that the latter
incorporates a deeper "air-spike" as an initial step in
the treatment. The two methods are analogous in form,
respectively, to the U.S. Navy's "Table 6" and
"Table 6A" (however, the depths at which 100% oxygen is
breathed is shallower, and the durations shorter for the IWR
methods than for the chamber schedules).

The primary purpose for
the deeper "air-spike" of the Hawaiian Method is
essentially to exert a greater pressure on the diver so that the
DCS bubbles are further reduced in size. In addition to restoring
circulation, the extra "overpressure" may facilitate
bubble resolution (Kunkle and Beckman, 1983; Farm
et al., 1986). Air is used instead of oxygen
because of the risk of acute CNS oxygen
toxicity which
results from breathing oxygen at such depths. Along with the
benefits of increased bubble compression, however, come the risks
of additional nitrogen absorption during this "spike".

To address the
therapeutic advantages of the "spike", it is important
to examine the physical effects of pressure on bubble size.
Although by Boyles Law alone there is a substantial
"diminishing of returns" in terms of bubble size
reduction as one descends deeper, gas phase bubbles are subject
to other forces that may affect their size. Although a discussion
of bubble physics is beyond the scope of this article, suffice it
to say that bubble radii are reduced proportionally more with
increasing depth than what would be predicted by Boyles Law
alone. Perhaps more importantly, the pressure of the gas within
the bubble increases proportionally more, which leads to
increased rates of bubble dissolution. However, the added risks
of nitrogen loading and nitrogen narcosis increase with depth,
adding potentially substantial greater risk to performing the
deep spike. A depth of 165 feet was chosen by the USN (Table 6A)
and Farm et al. (1986; the Hawaiian Method) as the
maximum at which benefit from recompression was significant.
Descent to a depth of 30 feet, the maximum depth prescribed by
the Australian Method, yields a nearly 50% reduction in bubble
volume, and approximately 20% decrease in bubble diameter.
Descent to 165 feet further reduces the bubble volume by an
additional 33%, and the diameter by an additional 25%. Thus, in
the case of bubble volume, more benefit results in the first 30
feet of recompression than is gained in the next 135 feet,
whereas the reduction in bubble diameter is slightly greater
during the subsequent 135 feet depth than the initial 30 feet.
Whether or not bubble diameter or bubble volume is more critical
to the manifestation of DCS symptoms is uncertain.

The fundamental question
is whether or not the additional recompression confers
physiological advantages sufficiently in excess of the
disadvantages associated with breathing air at depth (in an IWR
situation). Obviously, this depends on the immediate diving
history of the afflicted diver, and the particular circumstances
involved. The practice of subjecting DCS victims to a 165 feet
"spike" during chamber treatments has recently begun to
"fall out of favor" among hyperbaric medical
specialists. Hamilton (1993) points out that "the 6-atm
recompression with air or enriched air of Table 6A is likely to
be discontinued as evidence accumulates that it offers no real
benefit over the 100% oxygen [treatment] of Table 6". This
philosophy may also be applied to IWR treatment procedures. The
possibility of substituting EAN or high-oxygen Heliox during the
"spike" must also be examined. Modern technical diving
operations often involve EAN for some portion of the dive,
and thus EAN may be available in some DCS situations. EAN contains a percentage of oxygen
which is greater than 21%, and thus may offer therapeutic
advantages over air. The presence of nitrogen as a diluent in EAN allows a diver attempting IWR to
recompress at a greater depth than permitted by 100% oxygen (for
reasons associated with acute CNS oxygen
toxicity). In at
least one case (#13), EAN was used during IWR, with
apparently successful results. James (1993) outlines the benefits associated
with using 50/50 Heliox (50% helium, 50% oxygen) for
recompression therapy. Since helium mixtures commonly
incorporated into technical diving operations do not contain such
high proportions of oxygen, a supply of high-oxygen Heliox would
have to be maintained at the dive site specifically for the
purpose of IWR. Unless closed-circuit rebreathers are available
at the site, the option of using Heliox for IWR is probably
unfeasible.

There are a number of
safety advantages to the Australian Method over the Hawaiian
Method. Since the only breathing gas of the Australian Method is
oxygen, there is no risk of additional loading of nitrogen or
other inert gases. Thus, if the treatment must be terminated
prematurely (e.g. in response to the onset of nightfall; see Case #12), there is no risk of
aggravating the DCS symptoms. Furthermore, the
Australian Method may be conducted in shallow, protected areas
such as lagoons or boat harbors, where sea surface and current
conditions are less likely to be adverse.

We are unable at this
time to entirely condemn the Hawaiian Method of IWR, for it may
confer important advantages under certain circumstances. Edmonds
(1993) suggests
that the Australian Method of IWR is "of very little value
in the cases where gross decompression staging has been omitted",
presumably because such situations may require recompression to
depths in excess of 30 feet (9 meters) (although see Case #7 and #8). Under such circumstances (e.g.
`interrupted decompression' situations), the
"spike" might be advantageous. Nevertheless, we are
compelled to strongly discourage technical divers from
incorporating an "air-spike" into IWR attempts, at
least until additional verification of its efficacy can be
established through empirical and theoretical lines of evidence.

The USN method of IWR
differs from the Australian Method primarily in the recommended
ascent pattern. Whereas the Australian Method advocates a slow
steady (1 meter/12 min.) ascent rate, the USN Method divides the
ascent into two discrete stages at 20 and 10 feet. Although at
first this difference may seem trivial, it might, in fact, have
important physiological ramifications. Edmonds
(1993) reports
that "It is a common observation that improvement continues
throughout the ascent, at 12 minutes per meter. Presumably the
resolution of the bubble is more rapid at this ascent rate than
its expansion, due to Boyle's Law". If this is true, then
divers attempting IWR according to the USN Method could
conceivably suffer recurrence of symptoms immediately following
ascent to the next shallower stage. The validity of this argument
has yet to be verified.

Hyperbaric
Oxygen

All of the published IWR
methods advocate breathing an oxygen partial pressure of 1.9 atm
for extended periods. Such high levels permit increased
saturation of dissolved oxygen in the blood and tissues, which
may help provide badly needed oxygen to areas of restricted
circulation or tissue hypoxia. At such concentrations and
durations, however, the risks of acute CNS oxygen
toxicity are a
serious consideration. Oxygen partial pressures of 1.2-1.6 atm
have been suggested as the upper limit for technical diving
operations. The published IWR methods have endorsed exposure to
higher oxygen partial pressures because of the therapeutic
advantages, and because a diver performing IWR is apt to be at
rest (reducing the likelihood of an acute oxygen
toxicity
seizure). In at least one case (Case #7 above), the depth of in-water
oxygen treatment was limited to a maximum of 20 feet (oxygen
partial pressure of 1.65 atm) in an effort to avert oxygen
toxicity
problems. Because the consequences of convulsions resulting from
acute oxygen toxicity are particularly serious
underwater, all three published methods of IWR strongly recommend
that a tender diver be continuously present, and that oxygen be
administered via a full face mask. Although not prescribed in any
of the in-water recompression methods, most recent publications
discussing the use of oxygen as a decompression gas advise that the long periods
of breathing pure oxygen be "buffered" by 5-minute air
breaks every 20 minutes. The risk of additional nitrogen loading
from these brief periods is more than offset by the reduced risk
of acute oxygen toxicity problems.

Standard recompression
chamber treatments commonly incorporate breathing 100% oxygen at
a simulated depth of 60 feet (2.8 atm), however this should not
be attempted during IWR due to changes in human metabolism when
immersed in water, and to the grave consequences of an oxygen
toxicity-induced
convulsion underwater.

In
the Absence of Oxygen

Perhaps one of the most
critical conditions affecting the decision to perform in-water
recompression is the availability of 100% oxygen, especially in a
system capable of delivering it to a diver underwater. Although
the risk of acute oxygen toxicity symptoms is certainly a cause
for concern, the added advantages to effective decompression/recompression are tremendous.
However, there will be cases of DCS which occur in situations where
100% oxygen is unavailable. Surely, in light of the theoretical
disadvantages of attempting IWR using only air, such a practice
would seem absurd. Indeed, all of the cases for which IWR left
the divers in worse shape than when they began (e.g. Case #3 and #10), involved air as the only
breathing mixture. Furthermore, the diver in case #8 did not improve after air-only
IWR, and may have exacerbated his condition during his failed
attempts. Nevertheless, the vast majority of the reported
"successful" attempts of IWR (including Case #2, #4, #5, #6, and #11 above) were conducted using only
air. Several early publications proposed methods of air-only IWR
(e.g. Davis, 1962), however none are presently
recognized as practical alternatives to oxygen IWR.

In two of the above
cases of air-only IWR (#4 and #5), the afflicted divers followed
the advice of their decompression computers in determining an air
recompression/decompression profile, with apparent success.
However, as pointed out by Overlock (1989), use of computers for this
purpose "was never intended by the designer/manufacturer,
nor would it be recommended". The reason this practice is
not advisable is that the algorithms utilized by such devices for
determining decompression profiles do not account for the
complexities introduced by the presence of intravascular bubbles,
which can dramatically affect decompression dynamics (Yount,
1988).

Edmonds et al. (1981, p.
173) sum up air
IWR as follows: "In the absence of a recompression chamber,
[air IWR] may be the only treatment available to prevent death or
severe disability. Despite considerable criticism from
authorities distant from the site, this traditional therapy is
recognized by most experienced and practical divers to often be
of life saving value".

Our suggestion (and an
underlying message of this article), is that technical divers,
who are already familiar with the use of 100% oxygen underwater
as a decompression gas, should add to their
equipment inventory the necessary items (such as a full face mask
and large supplies of extra oxygen) to perform proper IWR
procedures. Having done this, these divers avoid facing the
decision to perform the risky gamble of air IWR.

Conclusions

It should be clarified
at this point that the main purpose of this article is to bring
forth the issue of IWR as an alternative response to DCS, and to summarize available
information on the subject. We do not necessarily endorse IWR;
however we see an increasing need by technical divers to become
aware of the information available on this topic. Several
disturbing facts have prompted us to bring this issue to light.
First, based on available reports, it is clear that many people
are attempting IWR without even knowing that published procedures
are available. Furthermore, most reported attempts were conducted
using only air. Although the practice seems to have led to a
surprising number of successful cases, the advantages of using
oxygen for IWR are tremendous, and cannot be denied. Thirdly, and
perhaps of greatest concern, few of the individuals who
successfully attempted IWR sought subsequent examination by a
trained diving physician.

We feel compelled to
strongly emphasize the importance of seeking a thorough medical
examination after any situation where DCS symptoms have been detected.
Regardless of how successful an attempted IWR procedure may be,
the affected divers should arrange for transport to the nearest
recompression facility as soon as possible to undergo examination
by a trained hyperbaric medical specialist. The practice of IWR
should never be viewed as an alternative to proper treatment in a
recompression chamber. Rather, it should be viewed as a means to
arrest and possibly eliminate a progressing or otherwise serious
case of DCS. In most cases, in-water
recompression should be used as an immediate measure to arrest or
reverse serious symptoms while arrangements are being made to
evacuate the victim to the nearest operating chamber facility.
Without doubt, a person suffering from DCS is better-off within the warm,
dry, controlled environment of a chamber, under proper medical
supervision, than he or she is hanging on a rope underwater.

The information
contained in this article is directed at the growing numbers of
"technical" divers, who are conducting dives which
expose them to elevated risk of sustaining serious DCS symptoms. These sorts of divers
tend to be more experienced and better prepared and equipped to
handle many of the procedures outlined by published IWR methods.
As put forth by Menduno (1993, p. 58), "In-water oxygen therapy
appears to be a promising, though perhaps transitional, solution
to the problem of field treatment for technical divers. Though
the concept will take some work to properly implement on a
widespread scale, the technical community does not suffer from
the same limitations as its mass market counterpart." By
"transitional", Menduno was no doubt referring to the
possibility that lightweight, portable recompression chambers may
soon become standard technical diving equipment, and may be
available on a much broader basis in the future. Selby
(1993) describes
one such chamber design which can be compactly stored and quickly
assembled in field emergency situations. Edmonds
(1993, p. 49),
however, cautions that:

"When
hyperbaric chambers are used in remote localities, often with
inadequate equipment and insufficiently trained personnel,
there is an appreciable danger from both fire and explosion.
There is the added difficulty in dealing with inexperienced
medical personnel not ensuring an adequate face seal for the
mask. These problems are not encountered in in-water
treatment."

In any case, the present
high cost of portable recompression chambers will prevent their
widespread availability anytime soon. Furthermore, there will
always be DCS incidents in situations where no
recompression chambers are available nearby.

Our intention is to
illustrate that the issue of IWR is far from clearly resolved. We
have little doubt that staunch opponents to the practice of IWR
will angrily object to even discussing the issue, on the grounds
that it might lead improperly trained individuals to make a bad
situation worse. But we adhere to the idea that the dissemination
of information to those who may need it is of utmost importance,
especially when lives may be at stake. It is indeed tragic when a
person suffering a relatively minor ailment resulting from DCS attempts IWR incorrectly and
leaves the water permanently paralyzed or dead. However, it is
perhaps equally tragic when a DCS victim ends up suffering from
permanent disabilities because of a long delay in transport to a
recompression facility, when the damage might have been reduced
or eliminated had IWR been administered in a timely manner. We
believe that the time has come to address this issue seriously,
openly, and with as much scrutiny as possible. Only through
further controlled experimentation and careful analysis of
reported IWR attempts will this controversial issue progress
towards resolution.

In an effort to document
larger numbers of IWR cases, we have begun to collect data on
this topic and intend to establish a database of reported IWR
attempts. If any readers have ever attempted IWR, or know of
anyone who has, we would be greatly indebted if copies of this
form could be filled out and mailed to Richard L. Pyle,
Ichthyology, B.P. Bishop Museum, P.O. Box 19000-A, 1525 Bernice
St., Honolulu, HI 96817; or sent by FAX to (808) 841-8968.